Fire pump
From Wikipedia, the free encyclopedia
A fire pump is a part of a fire sprinkler system's water supply and can either be electric or diesel. The pump intake is either connected to the public underground water supply piping, or a static water source (e.g., tank, reservoir, lake). The pump provides water flow at a higher pressure to the sprinkler system risers and hose standpipes. A fire pump is tested and listed for its use specifically for fire service by a third-party testing and listing agency, such as UL or FM Global. The main code that governs fire pump installations in North America is the National Fire Protection Association's NFPA 20 Standard for the Installation of Stationary Fire Pumps for Fire Protection.
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[edit] Operation
Fire pumps may be powered either by an electric motor or a diesel engine, or, very occasionally a steam turbine. If the local building code requires power independent of the local electric power grid, a pump using an electric motor may utilize, when connected via a listed transfer switch, the installation of an emergency generator.
The fire pump starts when the pressure in the fire sprinkler system drops below a threshold. The sprinkler system pressure drops significantly when one or more fire sprinklers are exposed to heat above their design temperature, and opens, releasing water. Alternately, other fire hoses reels or other firefighting connections are opened, causing a pressure drop in the fire fighting main.
Fire pumps are needed when the local municipal water system cannot provide sufficient pressure to meet the hydraulic design requirements of the fire sprinkler system. This usually occurs if the building is very tall, such as in high-rise buildings, or in systems that require a relatively high terminal pressure at the fire sprinkler in order to provide a large volume of water, such as in storage warehouses. Fire pumps are also needed if fire protection water supply is provided from a ground level water storage tank.
Types of pumps used for fire service include: horizontal split case, vertical split case, vertical inline, vertical turbine, and end suction.
[edit] Jockey Pump
A jockey pump is a small pump connected to a fire sprinkler system and is intended to maintain pressure in a fire protection piping system to an artificially high level so that the operation of a single fire sprinkler will cause an appreciable pressure drop which will be easily sensed by the fire pump automatic controller, causing the fire pump to start. The jockey pump is essentially a portion of the fire pump's control system.
[edit] In the U.S.
The application of a jockey pump in a fire protection system is covered by documents produced by the NFPA (National Fire Protection Association, ) known as NFPA 20 "Fire Pumps" Standard and NFPA 13 "Design and Installation of Fire Sprinkler Systems". These must be inspected as with any other part of the system per NFPA 25 "Inspection and Testing of Water-Based Fire Protection Systems". Fire protection systems are governed in most states by statute, building code, and/or fire code.
[edit] In India
This jockey pump is also a must while designing the Fire Hydrants Pumps skid for Industrial installations. While the logic followed for the effective operation of the fire fighting pumps may depend upon or vary as per the regulations in a particular country, in India, the pump manufacturers like Mather & Platt with standard Fire Pumps generally adhere to the TAC guidelines (Tariff Advisory Committee guidelines).
Although India's premier manufacturer Kirloskar Brothers Limited, with approvals from UL and FM Global, LPCB, ASIB: follows TAC guidelines (Tariff Advisory Committee guidelines), or FM GLobal and UL standards depending on the clients needs.
If one is following the TAC guidelines, follow this approach
- Once the complete fire fighting circuit is under pressure by operating the pumps for sufficient time provided all the fire hydrant valves (Single yard hydrants, Fire escape hydrants, etc)are closed, the main pump stops.
- Due to some leakages somewhere in the fire fighting piping circuit, when there is a loss of system pressure which will be constantly monitored by the Pressure sensors in the circuit, the jockey pumps receives a signal to start from the automatic control panel, and will run to augment this loss of pressure by pumping more water into the circuit. Once the pressure is maintained as per the set point, it stops.
- If any hydrant valve is opened due to some fire and water is consumed, then the jockey pump due to its small capacity compared to the main pumps (one running, one stand-by)in terms of volumetric capacity, the main pump will start and then the jockey immediately stops.
This way jockey pump is important which senses the loss of pressure in the circuit first.
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